1. Field of the Invention
This invention relates to a shock-absorbing spring for vehicles, particularly to one having a deformed egg-like cross section capable of lightening the spring, advancing stress enduring ability and spring travel.
2. Description of the Prior Art
Commonly, a shock absorber is installed in a chassis of a vehicle to effectively keep tires contacting on ground to minimize unnecessary jumps, shocks or impacts while running on an unsmooth road, providing a better cornering traction so that a driver can comfortably drive a vehicle.
As shown in FIG. 1, a conventional shock absorber is usually composed of a spiral spring that is easily made of round steel bar. But, such a circular cross-sectional shock absorber is restricted in its usable scope; so if a compressible length is to be stepped up, the spiral spring has to be lengthened, posing a heavy weight to make it hardly installed. Moreover, as stress is to concentrate at the inside of the spiral spring while the spiral spring is compressed, breakage may be apt to happen to shorten service life of the spiral spring.
In order to overcome the disadvantages of the circular cross-sectional spiral spring mentioned above, a rectangular and a trapezoid cross-sectional spring has been devised to further step up coefficient of elasticity (K value). However, the stress is as well to concentrate at the inside of the spring while the spring is stressed, restricting the compressible length. While the trapezoid spring can prevent stress from concentrating at the inside of the spring as the rectangular spring can, the compressible length is still unable to be further lengthened because the outer height (the bottom of the trapezoid) of the spring is too large. In addition, such a trapezoid spring is uneasy to be manufactured, thus not popular in practice.